Asked to set Windows pc name, date and time when using %serialnumber% variable

After adding the variable %SERIALNUMBER% or %AssetTag% to my task sequence to name the computer. I am getting the Windows setup screen to add a computer name and set the time and date. I am using SCCM 2012 R2 and MDT 2013. This is happening on HP 8300 elite but not a Dell 7010.

I have used the instructions found here http://www.techygeekshome.co.uk/2012/09/setting-computer-name-automatically.html

Does anyone know how I can stop this from appearing.